Should we vent our attic for new polyurethane closed-cell spray foam insulation?

All right. As soon as you see a headline beginning with "Losing Their Health and Homes to..." you should know that last thing the author has in mind is making your life better. The article is nothing more than atrocious clickbait. Do not make fundamental changes in your life or your home based on what somebody wrote purely to sell internet advertising.

Now, the EPA article can be trusted. But Margaret Badore, the author of "Losing Their Health...", is citing it in support of her super scary thesis. Does the EPA article actually say that SPF in your home is dangerous? It does not. Does the EPA article say you should be worried about SPF in you home? It does not. What it says is that the EPA is not absolutely certain that SPF poses no long-term danger.

In other news, the EPA is also not absolutely certain that composition decking, gas water heaters, iron nails, and NEST thermostats pose no long-term danger. Citing this EPA article in support of the long-term dangers of SPF is a pure and simple lie.

Badore gives the following evidence that SPF can cause health problems:

[Mr. Rimel] came down with respiratory symptoms [after visiting] the construction site of their new home where a contractor was installing spray polyurethane foam insulation.

and:

A couple in their 30's returned to their home four hours after spray foam was installed in the attic [and] almost immediately began experiencing difficult breathing, coughing, nausea, headaches and watery eyes.

Really. More than half of the text in the EPA article consists of every kind of warning against doing either one of these incredibly stupid things. Meanwhile Badore completely ignores the tens of millions of families happily occupying SPF-insulated homes with no ill health effects whatsoever.

The remainder of the EPA page is divided between (1) we don't know about the long-term effects and (2) removing the stuff usually makes the problem worse.

And the Rimels? Well, they searched out a company to test the site and guarantee its safety. Predictably, the testing company basically condemned the property. The Rimels panicked and removed the foam. It didn't help. The partially finished house had become haunted, for the Rimels and for anyone else who read the super scary test results.

After months of being unable to find a satisfactory solution, they sold the property.

Don't be like the Rimels.

first of all - don't panic about the polyurethane foam. PUF is not the same as UFFI from the seventies, but it does have problems if not done correctly. personally, i never use the stuff in any jobs and i think its going to go the same way of UFFI for ecological reasons. THAT DOES NOT MEAN YOUR HOME IS UNSAFE OR THAT ANYTHING IS WRONG!!!

essentially, spray insulation is a foam that forms and hardens once two chemicals are mixed in very specific proportions. if all the metering equipment is 100% accurate and calibrated, then both chemicals react in their entirety and there is no outgassing. however, if either of the proportions is off, you get almost all of it reacting with a small residual left that didn't react. it can be either chemical A or chemical B.

there are two major types of foams: polyurethanes and polyisocyanurates. now in most spray foams, there are two parts - the resin (which becomes the solid part in the foam) and the catalyst (which causes the bubbles in the foam) - remember, this is pretty simplified for non-engineers. the health problems come when there is too much of the isocyanate left over. so if your foam ingredients contain isocyanate, and it was installed with mis-calibrated equipment, then you can run into problems. if you have a little bit of unreacted material, it will off gas in a few days to weeks, but larger amounts may take years to offgas. its the latter of this type of scenario that creates nightmares. even if you scrape it all out, you will still have residual isocyanate.

unfortunately, contrary to popular belief, polyethylene vapour barriers do not stop the VOC's in these compounds from passage. so even if you have a 100% intact vapour barrier, you will still get some diffusion through into the living space.

primarily, you would have to ingest huge amounts of it to kill you (ld50 is 520-880mg/kg). its not carginogenic, but it can cause respiratory and cardiovascular problems. it usually just smells bad and gives you a headache and sore throat.

this would be my suggestion:

1) add fans to your attic space to ensure maximum removal of the gases before they get a chance to seep into the living area. you can get electric attic fans or just put a regular fan below roof vents temporarily rigged up to blow out through the vent.

2) if you are worried about your air quality, just get the air tested. just look for an air quality lab in your area. its fairly cheap and can give you empirical data to tell you whats going on in your home.

3) crank up the HRV if you have one, crack the windows and leave on the bathroom fans. your heating bill may go up, but your blood pressure may go down.

hope that helps

First of all, thanks to all who took the time to respond to my query! I thought that I should write in to let others know how I resolved the issue. I got the air tested by a local environmental testing firm and found out that there was hardly any sign of volatile organic chemicals VOC's in the house and no evidence of the chemical I was most worried about, which is MDI. Big relief! It would be normal to have low amounts of VOC's even without the spray foam because of other construction materials. Building codes say that you don't have to ventilate attic spaces where there is spray foam on the underside of the ceiling, because the SPI spray foam insulation will supposedly keep out any moisture, but it seems crazy to just seal off this space, so we are going to install some limited ventilation in the form of 2 bathroom-type fans: one blowing air from the attic to the outdoors and another blowing air into the attic from the living area of the house. We can't just put in vents from the attic to the outside without insulating all the ceilings on the second floor, because the attic is considered "conditioned space".
Side note - the SPI insulates really well. There were a few areas for skylights where we didn't install the foam on the roof sheathing and on 90 degree plus sunny days the uncoated roof sheathing in these areas became hot to the touch while the surface of the spray foam stayed almost cool. On balance I wish I hadn't installed it because of all the worry and the lack of information about what it will do 20 years down the road, but it is not a disaster, and has some benefits.

Do not be fooled by a Doom and Gloom article. Closed Cell foam is perhaps the greatest innovation in home building and remodeling in the last 30 years. I have had at least 6 buildings and homes sprayed with this product and the results have been nothing short of amazing.

For example, with only 1" of foam applied to the inside of a metal pole building that is 66'x104'x18 feet tall, i am able to keep it a comfortable 60+ degrees with a single small 120,000 btu heater at temps as low as -10 F.

Any measurable out gassing that might occur happens within the first weeks. After that, you are living in a YETI COOLER! (yes, the same insulation) All air infiltration is stopped. Warm air stays inside, cold air stays outside! This is the greatest benefit of this product, but must be taken into consideration if your indoor activities create lots of odors, etc.

In the houses I have had done, normal opening of doors, etc provide plenty of air transfer, along with the small air leaks you get around even the best windows and doors.

And dont forget the GREATEST issue with indoor air quality, MOLD. Fiberglass and loose fill insulation are practical breeding grounds for mold. Warm moist air enters wall cavity's, attics, etc where the moisture will ALWAYS condensate. This dark moist area is the perfect breeding ground for black mold.

the only solution is the addition of (usually ineffective) vapor barriers inside your home (that always have holes in them from staples, and for outlets, etc) and vented outside wraps (to make sure your walls are filled with cold dry air, which sort of defeats the purpose doesn't it)

Moisture CAN NOT penetrate this Closed cell insulation. There is ZERO condensation, zero mold. No chance of it happening. Warm on the inside, cold on the outside, no mingling of moist warm air with cold air.

I feel confident after remolding many older homes, and seeing the mold in the walls, that this product IMPROVES indoor air quality long term. And The energy savings alone contribute so much more to our environment and sustainability.

Be careful, there are lots of self-interested responses regarding safety (or lack thereof) of spray foams. While I would never use spray foam nor live in a tight home (<2ACH 50) with the stuff, a well-ventilated, or typical leaky code-compliant new construction (5+ACH 50) home is unlikely to generate high exposure levels to many carcinogens. 'Dilution is the solution'.

However, with the current fashion of super-tight homes (Passive Haus etc), I'd have significant reservations because tight homes rely on HVAC systems that require always-on ventilation. A badly designed, installed or maintained system can generate unsafe indoor air quality up to 10x worse than outside air. Early tight homes were particularly problematic as not enough always-on ventilation was provided, or there were dead spaces (often when bedroom doors were closed - people were sleeping in poorly-ventilated rooms all night). Recent design standards have increased recommended ventilation levels and newer designs require ventilation at every room.

That said, why risk living inside a foam-encased structure at all? Plenty of far-safer and less expensive insulations out there (blown-in cellulose, fiberglass). As for the 'why worry, it's safe because millions of homes use spray foam' argument, well asbestos and lead paint were used for centuries and thought safe too.

Bottom line, the sky is falling. All Spray foamed homes should be immediately condemned and razed - by hand of course and using only green approved processes. Then, the houses of the future will be built strictly from green recycled materials only. Of course they will be insulated using strands of non GMO flax plants hand-harvested by indigenous workers from green approved fields using only hand-hammered copper blade tools.

Then, all those who survived the years of exposure to sub-zero conditions will be “safe”. Since the brutal living conditions weeded out the weaklings by natural selection, the longer life span of those who survive the purge will then be pointed to as “proof” that the green revolution was all-wise.

Relax. Your properly foam insulated house isn’t going to kill you any faster than the dust from the gyp board, the outgassing from the chemical soup emulsion you smeared everywhere (aka “paint”) the “heavy metals” present in your electrical equipment, (lead, arsenic, antimony, etc.) or the “leaking poison gases” from your state of the art commercial cooking system (residual CO emissions from your awesome six burner commercial stove) or those stinky scented essential oil burners that you light and then place everywhere.